Black Algae Treatment

[PoolStored]

A thought for your situation. May be wonky, but could work.

Get threaded to SLP pvc joint that matches the threads on the return closest to the stairs. Mount a 90 degree elbow to it and another threaded coupler on the other side (Lets assume this coupler is female). Thread that into the return with the female threaded coupler facing toward the stairs. Make another section with a male threaded to SLP coupler to a piece of pipe long enough to reach the stairs, then cap it with a 90 degree elbow. Thread this second section onto the first section AFTER the first section is in place. You now have a pvc return section moving water on the stairs.

 

[Bperry]

Hi All, thank you again for the continued advice. It really helps.

I am now at nearly 2 weeks in elevated FC levels. I have kept the FC within about 22-26, which is just under SLAM for the CYA. The pH has improved, but still work to be done to keep it stable in the 7.4 range.

The BA seems to be *slowly* going away. I do feel like the surfaces are clearing up, but it is gradual. I know no two algae situations are the same, but does this timeline so far seem ok? I brush the BA daily, but I am a little worried using the steel brush so often on the same spots might damage the plaster. At 7-8 months of age, is the plaster still vulnerable? My other fear is that because the plaster was so young when the algae first showed up, it has been able to dig in deeper than on an aged pool surface.

I think one area I will always have problems is the stair steps. They do not have any nearby return, so the water in that area can easily stagnate. It was the first area to show BA, as well. Do you have any recommendations to improve water flow to that area? Is it possible to add extensions to other returns to get water moving over there? Maybe a wand or something to direct flow that way? Attached is a drawing of the situation.

Thanks!

If you run your pump 24x7 any circulation problem should be minimum.

Also, how are you testing pH? You can’t use the drip test when chlorine is over 10ppm. So I’d say don’t worry about the pH right now. I’d also use a nylon brush instead of stainless.

 

[Mithe86]

Yes, the pool runs 24/7 now, FC has been in the 17-26ppm this week and I still have not seen much progress with the black algae.

I have focused on a particular "test" area, and scrubbed that spot day after day, 2-3 a day, with wire brush and nylon and the black algae spots still do not come up. So far, the only really effective measure I've found is manually scrapping them with an ice pick to break the shell and let the chlorine in. Even now that we've been in elevated FC for 3 weeks, it has not cleared up any considerably amount.

Thoughts? Ideas? I'm running at the end of my patience rope and the copper algaecides are starting to look like a decent idea.

I was thinking maybe doing a major water change to get the CYA down under 40 or 50 (its 70 now) would help the chlorine be more effective? But even with high CYA, I've been at even higher FC to account for it and still no major improvement? One thing I've seen recommended is putting a puck of chlorine directly on the spots. I would try this again, but 1. it doesn't work for any BA on the walls, and 2. the pucks will introduce more CYA, right? Does anyone have a custom tool idea for applying concentrated liquid chlorine to an area, maybe 1% chlorine or something in the 30-100ppm range just for a few minutes?

I would like to avoid copper if I can to avoid staining, but nothing has seemed to work so far.

Thanks,
Michael

 

[PoolStored]

I was thinking maybe doing a major water change to get the CYA down under 40 or 50 (its 70 now) would help the chlorine be more effective?

I would in a heart beat...I also made this recommendation in post #3 of this thread...you have a way better chance to kill it at 40 than 70.

Pretty sure you know this but black algae seems to appear most frequently in pools that have been chronically underchlorinated. Not just days or weeks, but months.

 

[Mithe86]

I would in a heart beat...I also made this recommendation in post #3 of this thread...you have a way better chance to kill it at 40 than 70.

Pretty sure you know this but black algae seems to appear most frequently in pools that have been chronically underchlorinated. Not just days or weeks, but months.

I recall your recommendation, but I was hoping if you followed the calculator and just simply took the FC even higher to match that it would have the same net effect.

As for the black algae, it took root about 7-10 days after water was added to the pool (brand new).

I'll cut the CYA down and see what we can do. Thanks!

 

[PoolStored]

Does anyone have a custom tool idea for applying concentrated liquid chlorine to an area, maybe 1% chlorine or something in the 30-100ppm range just for a few minutes?

Some here have used pvc pipe put on the spot, then poured granulated chlorine into the pvc so it sits on the spot. This method typically has been used with organic stains.

 

[Bperry]

Is the only reason to not SLAM with black algae because it might take too long? When I had black algae spots, I just did the SLAM and it took about a week to clear up the black spots.

I’d try it in this situation but recognize it’s not what TFP recommends.

 

[mknauss]

Black ‘algae’ is not algae. It is CyanoBacteria. So the treatment is different.
This case , occurring 7 days after filling a new pool, is extremely rare.

 

[Mithe86]

Black ‘algae’ is not algae. It is CyanoBacteria. So the treatment is different.
This case , occurring 7 days after filling a new pool, is extremely rare.

Yes, I've had trouble finding anyone else with this condition. Is the recommended course to just continue with the elevated FC and scrubbing?

I'll do a partial water change to get the CYA down, but can I do anything else? I'm getting desperate.

 

[mknauss]

Not much else. You have to disturb the colonies to get chlorine to them.

You are sure it is Black Algae?

 

[duraleigh]

Agreeing with mknaus, I question that you have black algae. Can you post a pic(s)?

 

[Mithe86]

Have a look. If it's something else, please let me know. One picture shows a stair step from September. The largest spot has been cracked or crushed by me, which sometimes "outgasses" some black residue.


The second picture is from this past week, different location on the stairs. I've been studying the largest spot there (mid-upper left) to see if just brushing makes it go away (it hasn't). If I were to crush that spot with the ice pick, it would be gone in a day or two.


In short, the black organism will fill a pore of the plaster. You can see several little ones in both pictures, typically flush with the surface. When they get larger, they will sometimes start to protrude more.

The only success I've had with killing them is to crush them manually, which can be hard because they're very tough, like rock almost sometimes. The main benefit I've seen from the high FC, is that it hasn't spread or returned to places I've cleared... so at least it's containing it for now. Problem is that it's everywhere, bottom of pool has them all over, but not so concentrated yet that you can see it well. It appears just like dirt on the bottom of the pool from a distance.

 

[mknauss]

Was abalone shell used in the plaster mix?

 

[Mithe86]

Was abalone shell used in the plaster mix?

Not sure. Contract just said interior finish would be Quartz - Sky Blue. I can say that areas where I've manually cleared the black dots are back to the original look, and that these black dots do spread and grow with time, so I wouldn't think they're part of the plaster mix.

I've also had a few places where a major colony took root and bore a hole maybe 5mm wide and as you'd ice pick it, more and more black "dust" would come out until it was cleared out completely. This only happened in 2 or 3 spots.

 

[duraleigh]

I think the forum has seen something almost identical to that from another poster within the last year or so. I don't remember the outcome.

Black algae usually favors the grout at first. Assuming it is black algae, I would speculate that it may be holes that were in the pool surface to begin with and the black algae has taken up residence in those holes. I am only speculating.

 

[Mithe86]

Was abalone shell used in the plaster mix?

Builder confirmed there is no abalone shell in the plaster mix.

 

[mknauss]

OK. Next step is to try vitamin C. Could be iron specks from the mixing equipment.
Just checking off boxes.

Take a few tablets of vitamin C, put them in a sock, crush them a bit, and set them over a spot. Especially that spot that looks like the color spread out (your first picture).

 

[Mithe86]

OK. Next step is to try vitamin C. Could be iron specks from the mixing equipment.
Just checking off boxes.

Take a few tablets of vitamin C, put them in a sock, crush them a bit, and set them over a spot. Especially that spot that looks like the color spread out (your first picture).

Can the Vit C have rose hips?

 

[kul]

Seems rose hips is just more vitamin C so I’d go ahead and try it.

 

[Mithe86]

OK. Next step is to try vitamin C. Could be iron specks from the mixing equipment.
Just checking off boxes.

Take a few tablets of vitamin C, put them in a sock, crush them a bit, and set them over a spot. Especially that spot that looks like the color spread out (your first picture).

OK, I tried the c tablets and they didn't appear to have much effect. BUT, while I was down there I noticed that it seems like the algae is spreading for the first time in a while. I quickly checked FC and CYA and found them to be 21 and 65 respectively.

Then it hit me... it rained a lot last night after months of relatively dry weather... and our Spanish tile roof is black with algae.

Do you think the roof algae may migrate to the pool? We have gutters, but that doesn't stop all the splash off. I read roof algae is commonly "gloeocapsa magma", which is in the family of Cyanobacteria. Could this explain the persistence?

I'm going to have our roof cleaned immediately, as it's been on our to do list for a while.